truffle web3 synchronous request problem

Question

Error: Web3ProviderEngine does not support synchronous requests.

That's what I get when I use the following command from Truffle Console:

truffle(ropsten)> web3.eth.getBlock('latest').then(console.log)

Any ideas why this is happening?

The full error is as follows:

truffle(ropsten)> web3.eth.getBlock('latest').then(console.log)
Error: Web3ProviderEngine does not support synchronous requests.
    at ProviderError.ExtendableError (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-error/index.js:10:1)
    at new ProviderError (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-provider/error.js:17:1)
    at /usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-provider/wrapper.js:71:1
    at HDWalletProvider.send (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-provider/wrapper.js:109:1)
    at RequestManager.send (/usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/requestmanager.js:58:1)
    at Eth.send [as getBlock] (/usr/local/lib/node_modules/truffle/build/webpack:/~/web3/lib/web3/method.js:145:1)
    at evalmachine.<anonymous>:1:10
    at ContextifyScript.Script.runInContext (vm.js:59:29)
    at Object.runInContext (vm.js:120:6)
    at Console.interpret (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-core/lib/console.js:164:1)
    at ReplManager.interpret (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-core/lib/repl.js:119:1)
    at bound (domain.js:301:14)
    at REPLServer.runBound [as eval] (domain.js:314:12)
    at REPLServer.onLine (repl.js:468:10)
    at emitOne (events.js:116:13)
    at REPLServer.emit (events.js:211:7)
    at REPLServer.Interface._onLine (readline.js:282:10)
    at REPLServer.Interface._line (readline.js:631:8)
    at REPLServer.Interface._ttyWrite (readline.js:911:14)
    at REPLServer.self._ttyWrite (repl.js:537:7)
    at ReadStream.onkeypress (readline.js:160:10)
    at emitTwo (events.js:126:13)
    at ReadStream.emit (events.js:214:7)
    at emitKeys (internal/readline.js:420:14)
    at emitKeys.next (<anonymous>)
    at ReadStream.onData (readline.js:1011:36)
    at emitOne (events.js:116:13)
    at ReadStream.emit (events.js:211:7)
    at addChunk (_stream_readable.js:263:12)
    at readableAddChunk (_stream_readable.js:250:11)
    at ReadStream.Readable.push (_stream_readable.js:208:10)
    at TTY.onread (net.js:594:20)
truffle(ropsten)> 

Answer 1

As far as I can read it from your Stacktrace, you're using HDWalletProvider.

It seems like it doesn't support synchronous requests, so you'll have to pass a callback

web3.eth.getBlock('latest', function(err, res) {console.log(res)})

Moreover, web3.eth.getBlock('latest').then(console.log) will not work, since it's not a promise. If your provider would support synchronous calls, you would only have to call console.log(web3.eth.getBlock('latest'))